Optical Beam Control

Chapter 1Introduction

1.1 Optical Beam

The function of optical beam control is to meet the requirements of optical beams for pointing, pointing stability (jitter), quality of optical beams, slew maneuvers, object sensing, and tracking. It is a multidisciplinary field consisting of optics, control theory, structures, thermal analyses, vibrations, atmospheric turbulence, and lasers. This is a broad field, and this book will cover the fundamentals of each area with its applications to imaging satellites and laser systems.

Figure 1.1 shows the range of electromagnetic wave frequencies and wavelengths.

Figure 1.1 Electromagnetic wave frequencies and wavelengths.

The wavelengths of our interest are primarily in the visible range, 400–700 nm, and the near infrared range, 700–1100 nm. Because of small wavelengths, the requirements are challenging to meet, for example, typical telescope beam widths are 3–5 µrad. To mitigate most of the pointing loss, beam jitter should be less than 30% beam width, resulting in 0.9–1.5 µrad, pointing accuracy should be 0.1 times beam width, resulting in 0.3–0.5 µrad, and optical beam wave quality for diffraction limited performance, primary mirror surface RMS error, should be less than wavelength/30, 30 nm for the visible range. These requirements are very challenging and require state-of-the-art technologies to meet these performance requirements. ...